Line of sight stabilization systems are often used to conjugate and optically couple optical systems such as telescopes with light source modules and/or with light detection modules such as lasers and imagers commonly referred to herein as light modules. Line of sight stabilization systems allow variable orientations of the line of sight of the light modules with respect to the direction of the principal optical axis of the light module.
One known arrangement for such line of sight stabilization is commonly known as the Coudé telescope arrangement illustrated for example in FIGS. 1A and 1B. The Coudé telescope arrangement includes a telescope mounted on a stabilization assembly to which a light module receiving or transmitting light to the telescope is attached. The telescope includes a fixed internal mirror intersecting its optical axis inclined with respect thereto. The internal mirror operates to reflect light propagation along the optical axis of the telescope towards a light port of the telescope located alongside its optical axis (e.g. an eye piece can be installed in such a light port when the telescope is not mounted on the stabilization assembly). The stabilization assembly according to the Coudé arrangement includes a set of two gimbals connected to the body of the telescope, allowing its rotation about a pitch and roll direction being respectively a direction perpendicular to the telescope optical axis and a direction perpendicular to the pitch direction. The light module is mounted outside the gimbals and a set of mirrors, located on the roll gimbal, are arranged to provide optical coupling between the light port of the telescope and the light module.
Providing sustainable optical coupling between the telescope and the light module in various orientations of the telescope is obtained by setting the light port of the telescope in optical alignment with the pitch axis of the pitch gimbal such that the direction of light propagating therethrough is not affected by rotation of the telescope about the pitch axis. Additionally, an optical alignment between an optical port of the light module and the roll axis of the roll gimbal is set such that the direction of light propagating from the mirrors on the pitch gimbal towards the optical port is not affected by rotation of the pitch gimbal about the roll axis. Accordingly, optical coupling between the light module and the telescope is maintained while the orientation of the telescope can be changed relative to the light module.
Another example of a line of sight stabilization system is disclosed for example in US patent publication No. 2006/017816. In this publication, a line of sight stabilization system is described using two mirrors pivotally mounted to a fixed platform that can be used with existing imaging systems to provide pitch, roll, and yaw compensation while maintaining image orientation. By deflecting only the photons, the inventive system avoids the need to stabilize the entire imaging sensor and optics system. The only mass to move is that of the two imaging system mirrors. By monitoring attitude changes via an inertial measurement system, platform positions can be estimated for subsequent image acquisitions, and efficient mirror positioning can provide optimal image orientation and stabilization. This approach requires small motors with low torque, providing a less costly, lightweight, and small image orientation and stabilization system.